This invention relates to an ultrasonic diagnostic apparatus to be inserted into a body cavity for ultrasonic diagnosis.
The ultrasonic diagnostic apparatus of this type is so constructed that an ultrasonic transducer is housed in a distal end portion of an insertion section to be inserted into the body cavity, ultrasonic driving signals are transmitted from an external ultrasonic transmission-reception circuit to the ultrasonic transducer by means of a signal cable which is electrically connected with the ultrasonic transducer, and echo signals received by the ultrasonic transducer are returned to the ultrasonic transmission-reception circuit by means of the signal cable. In the case of an ultrasonic diagnostic apparatus of a mechanical-scanning type, the ultrasonic transducer need be mechanically rotated for scanning. If the ultrasonic transducer is rotated, however, the signal cable will rotate together with it and be twisted. Conventionally, therefore, the ultrasonic transducer is fixed so that ultrasonic scanning may be performed by reflecting ultrasonic waves from the ultrasonic transducer by means of a rotating mirror. According to such a rotating mirror system, only the rotating mirror need be rotated, so that the signal cable is kept from being twisted. In this case, however, the ultrasonic transducer and the rotating mirror must be contained in the distal end portion of the insertion section, so that the distal end portion will become too bulky to be inserted with ease into the body cavity.